Abstract:

【Objective】 Four popular midseason varieties of rice (Luoyou8, Guohaozayou1, Fengyou22 and Jufengyou72) were used to study the effects of application technology of nitrogen (N) on grain yield, grain quality and N-use efficiency in Hubei province. 【Method】Field trials with five N treatments (CK, FFP, modified FFP, SHY and modified SHY) and four replications were conducted synchronously at both Chibi County and Jingmen County, Hubei province in 2008 and 2009, respectively. 【Result】The results showed that grain yield of the control with no N application at Chibi was significantly lower than that at Jingmen both in 2008 and in 2009, which implied that soil N fertility in Jingmen was higher than that in Chibi. Grain yield of modified farmers’ fertilizer practice(FFP), super high yield (SHY) and modified SHY were more than that of FFP at Chibi with yield increase rates 10.0%, 2.3% and 23.2%, respectively, in 2008; and 16.6%, 11.8% and 22.6%, respectively in 2009. However, at Jingmen, grain yield of modified FFP, SHY and modified SHY were lower than that of FFP in 2008 and slightly more than that of FFP in 2009 with yield increase rates 2.0%, 6.7% and 1.7%, respectively. Nitrogen agronomic efficiency (AE) and nitrogen partial factor productivity (PFP) of modified FFP and modified SHY were higher than that of FFP in Chibi. PFP of N of above two treatments was significantly higher, while AE slightly higher than that of FFP at Jingmen. N-use efficiencies (NUE) of SHY at two field trial spots in two years were far lower than that of other treatments. 【Conclusion】 Both modified FFP and modified SHY treatments achieved higher grain yield and higher NUE, which suggested that 20% reduction of nitrogen of FFP could increase grain yield as well as NUE. On the contrary, too much N application would not increase, even reduce grain yield. In addition, the optimized nitrogen management could also improve the grain quality of rice.

Key words: N application, grain yield, grain quality, N-use efficiency